2. a "delayed" strategy where RRT (in patients who also present RIFLE F renal failure) is started only in case of occurrence of one or more of the following events ("Alert Criteria"): oliguria or anuria lasting for more than 72 hours after randomization, serum urea concentration > 40 mmol /L, serum potassium concentration > 6 mmol /L, serum potassium concentration > 5.5 mmol /L that persists despite well-conducted medical treatment with at least sodium bicarbonate and / or glucose-insulin infusion, arterial pH < 7.15 in the context of pure metabolic acidosis (PaCO2 <35 mmHg) or in the context of mixed acidosis with PaCO2> 50 mmHg without possibility of lowering this PaCO2 value, acute overload pulmonary edema generating severe hypoxemia requiring oxygen flow> 5L/min in spontaneously breathing patients or FiO2> 50% in mechanically (invasive or noninvasive) ventilated to maintain SpO2> 95%, despite diuretic therapy.